DESCRIPTION: (Applicant's Description) Pharmacologic induction of herpesvirus lytic cycle gene expression may be directly toxic to cells or may lead to expression of viral kinases. Viral kinases in turn may selectively activate nucleoside analogues that are directly toxic to cells or trap nucleoside analogues as to facilitate tumor imaging or therapeutic radiation. In preliminary experiments we have demonstrated killing of EBV and HHV-8 cell lines in association with pharmacologic induction of lytic cycle gene expression. We have also demonstrated that expression of recombinant EBV thymidine kinase and phosphotransferase genes and HHV-8 thymidine kinase and phosphotransferase genes lead to phosphorylation of ganciclovir as measured by HPLC and sensitize to cell killing with various nucleoside analogues. In aim 1, pharmacologic induction of lytic cycle with agents (butyrate and its analogues, bryostatin, and DNA, methyltransferase inhibitors) that are used or might be used clinically will be investigated. These agents will be studied in vitro, in a murine model and in peripheral blood specimens from patients treated with these agents. The activation of expression of lytic cycle genes including the viral kinases will be studied as well induction of cell death and the possible role of these agents in a tumor prophylaxis model. In aim 2, the viral kinases and various nucleoside analogues (ganciclovir, BVDU, penciclovir and zidovudine) will be studied. Direct measurement of enzymatic activities will be made and induction of cellular versus viral kinases differentiated. These investigations will be carried out in vitro and in a murine model and should help to determine whether there may be diagnostic or therapeutic applications for pharmacologic induction of gammaherpesvirus lytic gene expression in AIDS patients with herpesvirus associated tumors.